The most memorable part of this assignment was shooting Darwin's finches at the Tring branch of the British Natural History Museum, about 30 miles (50 kilometers) outside of London. The museum houses one of the largest and most complete ornithological research collections on the planet, but the specimens can only be seen by special appointment. The finches were a major source of inspiration for Darwin, and getting to see them up close, to have them arranged for me by the curators, to light them, and to make pictures of them was an extraordinary experience.

What was your worst experience in the field covering this story?

Time was the toughest thing to handle. I had about six weeks to complete shooting at 24 different locations in six countries and commonwealths: Russia, the United Kingdom, Jamaica, the Dominican Republic, Puerto Rico, and the United States. I shot most of the story using a large-format camera, which demands pretty powerful lighting. So I was traveling with 10 to 12 cases of equipment. You don't want to hear about the customs inspections and the excess baggage charges!

What was your quirkiest experience in the field covering this story?

It was strange to be working at the tuberculosis prison in Russia. We worked in masks and gloves for three days among inmates infected with a multiple drug-resistant strain of the disease. It was scary knowing they couldn't be cured.